The present invention relates to a device for active wheel alignment of wheels arranged on a wheel axle of a motor vehicle.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
Toe alignment of a wheel can be realized by a tie rod that is connected to the steering, or by an elastic-kinematic tie rod angle adjustment of the axle system, or by a combination of these two devices. Rear axles of vehicles in particular are known to have devices for active wheel alignment, whereby the tie rod is replaced by a servo unit. Such a servo unit can also be connected via a connection member with the tie rods of both sides. The servo unit adjusts the toe of the wheels of this axle in dependence on the driving conditions of the vehicle. Besides the use of servo units as tie rods, there is the possibility to realize a hydraulic servo unit, arranged centrally on a vehicle body or on the auxiliary rear axle frame, for active toe intervention of the rear axle. Two different steering strategies of the rear wheels are hereby distinguished: On one hand, a steering of the rear wheels in opposite direction to the front wheels at slow travel, in particular when parking the motor vehicle, and, on the other hand, a steering of the rear wheels in same direction in relation to the front wheels at fast travel, in particular when changing lanes or negotiating a curve.
There is the possibility to so configure a device for active toe and/or camber alignment as to utilize a movement (swaying, rolling) by the vehicle body, caused by the motor vehicle as it negotiates a curve, for targeted adjusting movements of the servo unit for influencing toe or camber. For this purpose, at least one of the body dampers, which are arranged between the vehicle body and the wheel axle, interacts with the servo unit in such a manner as to form a drive for the toe and/or camber alignment unit. As a result, it is possible to feed the active alignment of the motor vehicle wheels arranged on this wheel axle solely on the basis of the movement of the vehicle body. The body dampers trigger a flow of hydraulic liquid, when the vehicle sways or rolls, with the displacement of the hydraulic liquid operating a servo unit to adjust the tie rod. When the function of the active toe and/or camber intervention is not needed, e.g. when traveling straight ahead, which is also basic for the CO2 determination, the servo unit assumes a neutral position. The servo unit does hereby not consume any energy. The servo unit is not activated, even when two body dampers are evenly deflected on an axle. In this case, it would be of advantage when the body dampers in the form of telescopic vibration dampers convert the vibration energy of the body and wheel oscillations into heat. This should be possible in an appropriate way when traveling straight ahead as well as when negotiating a curve.
It would be desirable and advantageous to provide an improved device for active wheel alignment to obviate prior art shortcomings and to render it possible to maintain a damping function, when traveling straight ahead as well as when negotiating a curve, but in addition to utilize a fluid flow of a body damper for adjusting an external cylinder of a servo unit.